1. Field of the Invention
The present invention relates to a pencil sharpener, and more particularly to a reciprocating pencil sharpener to facilitate applying a rotational force and to perform an efficient pencil sharpening operation.
2. Description of the Prior Arts
A pencil sharpener is a device for sharpening the point of a pencil. A conventional pencil sharpener comprises a blade holder and a blade. The blade holder includes a conical bore therein to receive the point of a pencil. The blade is secured to the blade holder so that its cutting edge enters the conical bore. When it is desired to sharpen a pencil, the point of the pencil is inserted into the conical bore of the blade holder. The pencil is then rotated against the blade which cuts away the wood and lead of the pencil, thus sharpening the pencil.
However, the pencil must be rotated in continuous unidirectional rotation to be sharpened, and human wrists have limited ranges of motion. Thereby, after a user's hand holding the pencil rotates an angle, the hand should loosen and re-hold the pencil again to repeat rotating motion until sharpening operation is achieved. Each time re-holding the pencil changes the point of application of a rotational force. Re-holding the pencil frequently makes it difficult to apply a rotational force, affects the smoothness of pencil sharpening operation and thus reduces the efficiency of pencil sharpening operation.
GB Patent No. 2289445, entitled “Spring-driven Pencil Sharpener”, disclosed a pencil sharpener having a spring-driven powering device providing a power for rotating a blade set and having a spring and a rope. When the rope is pulled, the blade set is rotated. When the rope is released, the rope is pulled back to wind around a rope-strain reliever with the potential energy provided by the rotatably deformed spring. However, the pencil sharpener of the '445 is complicated and is troublesome in use.
U.S. Pat. No. 2,307,119, entitled “Pencil Sharpener” disclosed a pencil sharpener having a rotatable sleeve-like member that is rotated to drive a sharpening device to rotate to sharpen a pencil. In addition, the '119 patent further has a spring provided to continuously force the sharpening device toward the larger end of a casing, so the spring is a necessary component for the operation of the pencil sharpener of the '119 patent. Therefore, the pencil sharpener of the '119 patent has a complicated structure.
To overcome the shortcomings, the present invention provides a reciprocating pencil sharpener to mitigate or obviate the aforementioned problems.